Whipstocks are used in the process of drilling a secondary or deflection hole from a cased hole in underground rock or geologic formations. Such secondary holes or windows can be used to change a direction of a wellbore, to provide multiple paths from a single wellbore, or for dealing with formation problems. Prior procedures for milling a window in a casing have included the placement, orientation, and securing of the whipstock and subsequent drilling which has involved many steps. Subsequently, a one-trip window-cutting system was developed and is fully described in U.S. Pat. No. 5,109,924 to Jurgens. The combination of mills preassembled to a whipstock, as illustrated in the Jurgens patent, allowed the milling of the window from start to finish after the whipstock was properly oriented and supported.
In most operations, correct orientation of the whipstock face is required. Typically, if the wellbore has even a slight inclination, the whipstock face is oriented relative to the high side of the hole, and previous systems have only worked with whipstocks set to no more than 60 degrees to the left or right of the high side. The whipstock assembly is oriented using one of an orienting sub, steering tool, surveying device, etc. or by measurement while drilling. The orientation of the whipstock dictates the direction of the window and exit for running drilling bottom hole assemblies, liners, and completion equipment, and therefore the orientation of the whipstock is an important step in the process.